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EVC for 3DNow! (special case)

Future generations of AMD processors will not include 3DNow! CPU instructions. EVC mode is updated accordingly to hide this feature from older generation’s processors. So hosts which have 3DNow! Instructions will not be compatible with future generations AMD processors unless EVC mode is enabled. As future generation AMD processors will not have 3DNOW CPU instructions. So EVC mode must be enabled for vMotion compatibility between 3DNow! And Not 3DNow! CPU instructions. All AMD Opteron generations 3 are no 3DNow. Generations1 and 2 cannot be made vMotion compatible with hosts that have 3DNow! Instructions

AMD Opteron Gen.3 (no 3DNow) cannot be enabled while there are powered ON Virtual Machines in the cluster

Either migrate virtual machines out of the cluster or power off them. Migration only allows you to schedule a more convenient down time for virtual machine.

Configure EVC cluster by editing VMware EVC settings

If you have migrated virtual machines out of the cluster, power them off and cold migrate them back into the cluster.refer point 1

vCenter compares CPU features of Virtual machine with that of CPU features of the destination host to determine whether to allow or disallow migrations. In cases where you have to decide whether to maintain vMotion compatibility or enhanced CPU feature which guest OS might need, VMware provides check-box to configure individual Virtual Machine.You can configure more advance features as well at the bit level.